Solar Carboreduction of Alumina under Vacuum

AbstractMain requirements for successful production of aluminum via carboreduction of alumina using solar vacuum reactors are sufficiently high reaction temperature, suitable low partial pressure of the product gases, fast heating and quenching at temperature low enough to prevent backward reaction. Based on these requests a batch solar reactor was modeled, designed, built and tested. Experimental results of the solar tests under different vacuum levels and temperature conditions will be presented. It will be shown that for reaction temperature, which is above the minimal temperature required for full conversion as predicted by thermodynamic calculations for appropriate pressure, the alumina to aluminum conversion is above 90%. Not reaching the full conversion can be explained by the byproducts formation during the initial preheating. At lower reaction temperatures and higher CO partial pressure by products can also be formed when reaching steady state condition both in the forward and backward reactions. This formation in the forward reaction is confirmed by the discovery of larger amounts of Al4C3, Al4CO4 solids as the residual byproducts in the reactants holder and higher alumina content in the deposits on the cold parts of the reactor that originated from the volatile Al2O produced in the forward reaction which during the deposition converts to alumina and aluminum. Decreasing the reaction temperature is accompanied by decreasing the temperature in the hot zone that causes the increasing of the deposit mass there with higher amount of Al4C3 and Al4CO4 produced in the backward reaction. Nano crystalline and amorphous morphology of the deposits in the cold zone caused by fast cooling will also be discussed

Interaction of Copper-Based Nanoparticles to Soil, Terrestrial, and Aquatic Systems: Critical Review of the State of the Science and Future Perspectives

In the past two decades, increased production and usage of metallic nanoparticles (NPs) has inevitably increased their discharge into the different compartments of the environment, which ultimately paved the way for their uptake and accumulation in various trophic levels of the food chain. Due to these issues, several questions have been raised on the usage of NPs in everyday life and has become a matter of public health concern. Among the metallic NPs, Cu-based NPs have gained popularity due to their cost-effectiveness and multifarious promising uses. Several studies in the past represented the phytotoxicity of Cu-based NPs on plants. However, comprehensive knowledge is still lacking. Additionally, the impact of Cu-based NPs on soil organisms such as agriculturally important microbes, fungi, mycorrhiza, nematode, and earthworms are poorly studied. This review article critically analyses the literature data to achieve a more comprehensive knowledge on the toxicological profile of Cu-based NPs and increase our understanding of the effects of Cu-based NPs on aquatic and terrestrial plants as well as on soil microbial communities. The underlying mechanism of biotransformation of Cu-based NPs and the process of their penetration into plants has also been discussed herein. Overall, this review could provide valuable information to design rules and regulations for the safe disposal of Cu-based NPs into a sustainable environment

Continuous tracking of heliostats

ABSTRACT Tracking motions in current heliostats are usually performed in discrete steps, even though the motion of the sun is continuous. Aiming errors due to the discrete steps are often about 1 mrad or more. A significant reduction of tracking error by smooth continuous tracking is presented. The implementation uses an electronic speed control unit to modify the rotational speed of the two AC motors on an existing heliostat. The continuous tracking system was implemented and successfully operated at the Weizmann Institute heliostat field. Measurements of heliostat motion show that aiming error due to tracking intervals was practically eliminated. A comparison of heliostat motions and flux on the target in step-tracking and continuous tracking modes is reported

Fractionation of tomato fruit chromoplasts

Chromoplast differentiation involves an active synthesis of carotenoids associated with the remodeling of the preexisting plastid membrane systems to form specialized structures involved in the sequestration and storage of the synthesized carotenoids. These subplastidial structures show remarkable morphological differences and seem to be adapted to the accumulation of particular carotenoids in some plant species and organs. At present, very little is known about chromoplast biogenesis and the role of the different suborganellar structures in the synthesis and storage of carotenoids. The combination of classical fractionation methods with the use of biochemical and -omics techniques represents an attractive approach to unravel novel aspects related with the biochemical and cellular mechanisms underlying the biogenesis of the structures involved in the biosynthesis and storage of carotenoids during chromoplast differentiation. Here we describe a combined protocol for the isolation, lysis and fractionation of tomato fruit chromoplast. The fractions obtained are suitable for metabolomics and proteomics analysis.We acknowledge the financial support of AGAUR-Generalitat de Catalunya (Grant 2017 SGR 710), the CERCA Programme of the Generalitat de Catalunya and the Severo Ochoa Programme for Centres of Excellence in R&D 2016–2019 to CRAG (SEV-2015-0533). AB is member of the Spanish Carotenoid Network (CaRed) funded by the Spanish Ministry of Economy and Competitiveness (Grants BIO2015-71703-REDT and BIO2017-90877-REDT).Peer reviewe